Backfired again

chrisgarrett46 · 10-01-2008, 09:00 PM

This is the 4th time in the last few fews that I have been driving along and get into the gas and the car backfires very loud. The car runs great otherwise, and the coil pack ohmed at 12.5 to 12.8. Any ideas?

tony moore · 10-01-2008, 09:09 PM

chris, my car backfired alot when i first started driving it. after some loose grounds,coil module and crank sensor change it stopped. I think the module fixed the back firing. the crank sensor fixed the intermediate stalling. HTH

gbsean · 10-01-2008, 09:18 PM

it is chilly in Chi-Town did you adjust the alky....

chrisgarrett46 · 10-01-2008, 09:26 PM

Yeah, it's chilly now, but it did it when it was warm too.
I have the alky set at 6, and usually see about 10.8 on the wb at wot. Could the coilpack be at fault even if it ohms at 12.5?

challengermike · 10-01-2008, 10:45 PM

Battery wire hitting the exhaust manifold will cause that also.1 other thing to try would be ,my car for some reason if i am lower than 7 gallons of gas it will pop also.I am thinking it might be a tank with no baffles in it causing the fuel to slosh to the back leaving the pump to suck air.

GNVYUS 1 · 10-02-2008, 12:19 AM

If the coil packs old ( like 50k ) it's going to be harder for it to fire off boost with alky and could easily backfire like that on a rich mixture.

Why not lean it out into the mid 11's and see what happens?
It's possible the AF/R is going fatter than high 10's during spool up and that's were it's backfiring or the opposite, it's super lean like old blow through cars experience and blows the bonnet in half.

Russ Merritt · 10-02-2008, 01:55 PM

Double check your cam sensor adjustment.

chrisgarrett46 · 10-02-2008, 02:32 PM

Quote:

Originally Posted by Russ Merritt

Double check your cam sensor adjustment.

Will do.

Can the coilpack ohm out at 12.8 and still be at fault and what about the ignition module. I've been reading that a lot of guys swap them out and their backfiring issues are fixed.

earlbrown · 10-02-2008, 02:52 PM

Quote:

Originally Posted by chrisgarrett46

Will do.

Can the coilpack ohm out at 12.8 and still be at fault and what about the ignition module. I've been reading that a lot of guys swap them out and their backfiring issues are fixed.

Yes, when you measure the resistance on the top of the coil you're only measuring the secondary side for resistance (and not under real world conditions). There's a primary side of the coil that can be accessed from underneath. (and also not measured under running conditions under load)

Clear as mud?

turbomonte2 · 10-03-2008, 08:50 AM

Ohming OK (say 11-13) cold does not necessarily guarantee proper coil performance at higher, operating temps. Also, I've had bad ICM's that ck-out OK (cold also) on a tester (Wells?) at AZone--so go figure!

Best to just try "known good" coilpack & ICM--preferably GM,,,

Check clearance on crank sensor (both sides)--should be approx. equal & typically be 0.022-0.025",,, and, ck the cam sensor--turn 1/8" CCW at a time (until engine won't start) & then return to last position where it did start OK...

Orlando_87GN · 10-03-2008, 12:08 PM

I've ohmed coilpacks before that came up 'open' or nodda ohms. Car still ran great, so that test to me is worthless.

chrisgarrett46 · 10-06-2008, 07:49 PM

Hey guys. I forgot to mention that I took out 3.2 degrees of timing. Could that have anything to do with it?

gbsean · 10-06-2008, 08:26 PM

Quote:

Originally Posted by chrisgarrett46

Hey guys. I forgot to mention that I took out 3.2 degrees of timing. Could that have anything to do with it?

from what to what..... if the spark is not igniting all the fuel..that can happen...it can also happen if you dont have enough fuel as i found out on Friday night...don't go WOT with 1/8th of a tank of gas....

BEACH BUM · 10-06-2008, 08:30 PM

Chris, remove the battery cable and let the chip go back to it's default settings. Try it again.

tony moore · 10-06-2008, 08:34 PM

Quote:

Originally Posted by chrisgarrett46

Hey guys. I forgot to mention that I took out 3.2 degrees of timing. Could that have anything to do with it?

so was it backfiring before you took the timing out? if not I would put it back in and try it.I know less than most about tuning these cars, but low timing will cause a backfire.

10-01-2008, 09:00 PM	#1 (permalink)
chrisgarrett46 Out, damned knock Join Date: May 2004 Location: Highland Park, ILLinois Posts: 5,603	Backfired again This is the 4th time in the last few fews that I have been driving along and get into the gas and the car backfires very loud. The car runs great otherwise, and the coil pack ohmed at 12.5 to 12.8. Any ideas? __________________ Experience is what you get when you don't get what you want. 2008 rebuild, Comp roller cam, Cat stroker, RJC gridle, CPT66BB, PTE Stock Location IC, Champion iron, T&D roller rockers, 60# Mototron injectors w/Turbotweak chip, Monroe-ported throttlebody, RJC Power Plate, Jimmy-built trans w/Precision Vigilante converter, ATR SS dual exhaust, ATR rear sway, BMR upper and lower control arms, Edelbrock Performance shocks, Razor alky, Tinman cold air intake, MT street radials. Oh, and Russ Merritt spark plug wires.

10-01-2008, 09:09 PM	#2 (permalink)
tony moore old skool Join Date: Feb 2004 Location: South carolina Posts: 3,718	chris, my car backfired alot when i first started driving it. after some loose grounds,coil module and crank sensor change it stopped. I think the module fixed the back firing. the crank sensor fixed the intermediate stalling. HTH __________________ 86 grand national 2nd owner t tops, digital dash and few other options. bone stock no mods(yet!!) brought back from the dead. new paint and interior 85 regal t type clone, blue in and out , carb. turbo stock engine , no ecm, msd btm,holley blue fuel pump, 650 holley double pump carb. 3.73 gear with mini spool,all the gauges, stock trans and conv. slow but fun!!

10-01-2008, 09:18 PM	#3 (permalink)
gbsean 1 of 64,000,000 Join Date: Jul 2005 Location: Flanders, N.J. Posts: 10,656	it is chilly in Chi-Town did you adjust the alky.... __________________ 11.599 @ 119.91 eat that Ferret Joe and JoeNational Tuning in Progress Sean Ryder Buick Performance Group Vice-Chairman www.buickperformancegroup.com see thread for Engine Specs http://www.turbobuicks.com/forums/wa...tml#post680751 happy now Rich

10-01-2008, 09:26 PM	#4 (permalink)
chrisgarrett46 Out, damned knock Join Date: May 2004 Location: Highland Park, ILLinois Posts: 5,603	Yeah, it's chilly now, but it did it when it was warm too. I have the alky set at 6, and usually see about 10.8 on the wb at wot. Could the coilpack be at fault even if it ohms at 12.5? __________________ Experience is what you get when you don't get what you want. 2008 rebuild, Comp roller cam, Cat stroker, RJC gridle, CPT66BB, PTE Stock Location IC, Champion iron, T&D roller rockers, 60# Mototron injectors w/Turbotweak chip, Monroe-ported throttlebody, RJC Power Plate, Jimmy-built trans w/Precision Vigilante converter, ATR SS dual exhaust, ATR rear sway, BMR upper and lower control arms, Edelbrock Performance shocks, Razor alky, Tinman cold air intake, MT street radials. Oh, and Russ Merritt spark plug wires.

10-01-2008, 10:45 PM	#5 (permalink)
challengermike Registered User Join Date: Apr 2008 Posts: 81	Battery wire hitting the exhaust manifold will cause that also.1 other thing to try would be ,my car for some reason if i am lower than 7 gallons of gas it will pop also.I am thinking it might be a tank with no baffles in it causing the fuel to slosh to the back leaving the pump to suck air. __________________ 86 t type,6157 turbo,msd 50s,hotwired 340,3" dp ported elbow,comp 260 cam,smc alky,speed pro forged pistons .30 over,mild homeported heads,pypes exhaust with testpipe,f body rad with ramchargers fan.Best time 7.59 at 89 with a 1.66 60 foot in the 1/8 mile.

10-02-2008, 12:19 AM	#6 (permalink)
GNVYUS 1 Registered User Join Date: Feb 2004 Location: IL Posts: 856	If the coil packs old ( like 50k ) it's going to be harder for it to fire off boost with alky and could easily backfire like that on a rich mixture. Why not lean it out into the mid 11's and see what happens? It's possible the AF/R is going fatter than high 10's during spool up and that's were it's backfiring or the opposite, it's super lean like old blow through cars experience and blows the bonnet in half. __________________ Mike 87GN T-Top down 423lbs. Rebuild #2, BLK/BL Paint w/Custom Metal Flares, VPE Stg 3 Heads, 210/215 Roller Cam, TA49, V2 w/Blitz Blow Off, Billet Drum/Input, PI 3400 5disc, T Brake, Inland 3.5" DS, KB Plenum/70mm TB, Razor's Post Turbo Alky Kit, Devils Pre Turbo Alky Kit, 60lb Inj, Denso 280 Pump,-8/-6 SS Fuel Lines, MBC, Pwr Plt, PTE Oil Relocator, Preluber, Z06 Maf, Translator, Volt Master, Poston Headers, THSS 3.5" DP/Test Pipe, SS 2.5" Y Pipe w/No Muffs, PST 2" Drop, Poly Bushings, Boxed Upper/Lower Arms, QA1 Shocks, Vacuum Converted, Aerospace 11" Brakes w/SS lines, Alum Drums, Polished Autodrags 15x8/15x10, Nitto 555R 275/60's

10-02-2008, 01:55 PM	#7 (permalink)
Russ Merritt Registered User Join Date: Aug 2002 Location: Carver, MA USA Posts: 359	Double check your cam sensor adjustment.

10-03-2008, 08:50 AM	#10 (permalink)
turbomonte2 Older--but Getting Wiser Join Date: Sep 2004 Location: Myrtle Beach, SC Posts: 2,020	Ohming OK (say 11-13) cold does not necessarily guarantee proper coil performance at higher, operating temps. Also, I've had bad ICM's that ck-out OK (cold also) on a tester (Wells?) at AZone--so go figure! Best to just try "known good" coilpack & ICM--preferably GM,,, Check clearance on crank sensor (both sides)--should be approx. equal & typically be 0.022-0.025",,, and, ck the cam sensor--turn 1/8" CCW at a time (until engine won't start) & then return to last position where it did start OK... __________________ Monte 87GN, TE60, 23#, 60#Injrs, 214/214 hyd roller, Mild-ported hds & int, Dutt Nk, V booster, Old-style SMC alky, Q-Boost, Remote Oil Filter/Turbo Saver, KB 3" down & test pipe w/ cut-out, TTwk93-alky, SM 2.1, 3000 stall CK 10.5" L/U, CK Stg2 tranny kit+ some hard parts, Ext trans cooler, Dual 2.5" Hookers, Frt & bk braces, Hollow 36mm frt bar + Bilsteins, Air Bags + KYBs, Hotwired Wlbro/Racetronix GSS340M(new), 255x60x15 street meats, Factory Astroroof...Just replaced as my Daily-Driver by a '00 Ford Focus. Some other stuff laying around: 51 Merc Cpe, 49 Ford/T-Bird, 83 Riviera Conv, 96 F-150 5.8L "Pig" 4x4 tow vehicle, '00 Ford Focus as "new" Daily Driver... Last edited by turbomonte2 : 10-03-2008 at 08:51 AM. Reason: typo

10-03-2008, 12:08 PM	#11 (permalink)
Orlando_87GN Resident Idiot Join Date: Sep 2000 Location: Orlando, FL USA Posts: 10,458	I've ohmed coilpacks before that came up 'open' or nodda ohms. Car still ran great, so that test to me is worthless. __________________ Check Out MikesStuff4Sale.com to view my used parts! ------------------------------------------------ 1987 Buick Grand National Budget 4.1, 204/214 cam, TA-49 Turbo, Stockish Heads, V4, MSD50's, TH DP, JayJackson 62mm TB, Translator plus Extender powered. 3680# with pilot ------------------------------------------------ 1993 Mazda RX-7 4.1 Buick Powered 11.20 @ 128mph (2.4 60')!

10-06-2008, 07:49 PM	#12 (permalink)
chrisgarrett46 Out, damned knock Join Date: May 2004 Location: Highland Park, ILLinois Posts: 5,603	Hey guys. I forgot to mention that I took out 3.2 degrees of timing. Could that have anything to do with it? __________________ Experience is what you get when you don't get what you want. 2008 rebuild, Comp roller cam, Cat stroker, RJC gridle, CPT66BB, PTE Stock Location IC, Champion iron, T&D roller rockers, 60# Mototron injectors w/Turbotweak chip, Monroe-ported throttlebody, RJC Power Plate, Jimmy-built trans w/Precision Vigilante converter, ATR SS dual exhaust, ATR rear sway, BMR upper and lower control arms, Edelbrock Performance shocks, Razor alky, Tinman cold air intake, MT street radials. Oh, and Russ Merritt spark plug wires.

10-06-2008, 08:30 PM	#14 (permalink)
BEACH BUM Registered User Join Date: Aug 2008 Posts: 900	Chris, remove the battery cable and let the chip go back to it's default settings. Try it again. __________________ " It is best to start safe and work up to ones own tune even tho' this takes a bit of work and many don't consider this to be fun in the plug n generation. Those that take the time and effort, probably last longer than those that just want a number." Steve Wood

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